Hydronephrosis is a back up of urine into the kidney and is usually graded as mild, moderate or severe depending on the accumulation of fluid and how much it extends into the kidney. It is usually caused by some type of obstruction in the ureters which are the tubes that connect from the kidney to bladder. This is easily seen on ultrasound.
Not sure what the term "normal" means. Like Clark said, this isn't normal but was it expected due to a complication in the surgery and they are addressing it? I assume you are getting information from your recipient as the team would most likely not discuss his/her health with you, the donor. Does the recipient understand all the information being presented? It is very overwhelming to go to these appointments, as there is often a lot of information given in a short period of time. So perhaps something was not understood properly. But I have to agree with the others, hydronephrosis is not normal.
Hope you get clarification.
All the best,
Sherri